1. Field of the Invention
The present invention relates to a condenser for a vapor recovery apparatus of an imaging system. More particularly, this invention is directed to a condenser for a vapor recovery apparatus of an imaging system having a vapor generator for generating fine bubbles in a carrier vapor so that the carrier vapor is more effectively condensed.
2. Description of the Related Art
In general, an imaging system, applied to a printer or a copier, uses a photosensitive medium such as a photoreceptor drum or a photoreceptor belt, on which a latent electrostatic image is formed.
The imaging system is largely divided into a wet type and a dry type according to the type of toner used. Tile liquid imaging system employs a developer liquid having a toner mixed with a volatile liquid carrier. The liquid imaging system using such a developer liquid has a better printing quality than the dry imaging system using a powdered toner, and also protects against ill effects of the harmful toner powder, and thus, is being used increasingly.
Referring to FIG. 1, the typical liquid imaging system includes a photoreceptor belt 110 on an endless track, a first transfer roller 121, a second transfer roller 122 and a third transfer roller 123, for circulating the photoreceptor belt 110 in a given path.
Also, a main charger 135 is installed at one side of the photoreceptor belt 110 for charging the surface of photoreceptor belt 110 into uniform charges. In the lower portion of the photoreceptor belt 110, there are provided a laser scanning unit (LSU) 130 for scanning a laser beam onto the photoreceptor belt 110 according to an image signal and to form a latent electrostatic image, and a development device 140 for developing the latent electrostatic image into a toner image by applying a developer liquid composed of a toner having a predetermined color to a region where the latent electrostatic image is formed. Particularly, in the case of a color printer, there are provided a plurality of laser scanning units (LSUs) 130 for color image implementation and a plurality of development devices each containing a developer liquid having a predetermined color.
As described above, since the liquid carrier is contained in the developer liquid which sticks to the latent electrostatic image region of the photoreceptor belt 110, the carrier is removed in a drying unit 150 after the developing of the latent electrostatic image. The drying unit 150 includes a drying roller 151 and a heating roller 152 installed parallel to and spaced a predetermined distance apart from the third roller 123. The drying roller 151 absorbs the liquid carrier from the surface of the photoreceptor belt 110 and dries the developer liquid so that only the toner image remains. The liquid carrier absorbed into the drying roller 151 is heated by the heating roller 152 and evaporated to then be removed.
FIGS. 2 and 3 illustrate a carrier gas recovery apparatus provided in the vicinity of the drying unit 150 in the conventional liquid imaging system having the aforementioned configuration. FIG. 2 is a block diagram of a carrier gas recovery mechanism of the carrier recovery apparatus and FIG. 3 is a schematic diagram of the carrier recovery apparatus.
Since the carrier evaporated by the drying unit 150 is harmful to humans, it is necessary to prevent the evaporated carrier from being effused to the air. Also, in order to decrease operating costs, it is necessary to reduce the overall consumption of the liquid carrier by recycling the liquid carrier. Thus, there is generally provided a carrier gas recovery apparatus for recovering the carrier gas as a liquid carrier by collecting and condensing the carrier evaporated by the drying unit 150.
Referring to FIG. 2, the carrier gas recovery mechanism of the conventional liquid imaging system will now be described. The carrier gas evaporated by the drying unit 150 is collected by a collector 160. Part of the carrier gas is liquefied in the collector 160 and the remaining carrier gas is sent to a condenser 170 to be condensed and then liquefied. The liquid carrier is sent to a recovery reservoir 180 for recycling. The air from which the carrier gas is removed while passing through the condenser 170 is exhausted outside via a filter 190.
As shown in FIG. 3, the drying unit 150 includes the drying roller 151 and the heating roller 152. The drying roller 151 is installed parallel to and spaced a predetermined distance apart from the third roller 123 and absorbs the liquid carrier sticking to the photoreceptor belt 110. The heating roller 152 evaporates the absorbed liquid carrier.
The collector 160 installed to surround the drying unit 150 collects the carrier gas. Part of the collected carrier gas is again liquefied and sent to the recovery reservoir 180 installed under the collector 160. Most of the remaining carrier gas is sent to the condenser 170. The cold liquid carrier is contained in the condenser 170.
A gas duct 171 for inducing the carrier gas from the collector 160 and an air exhaust tube 174 for exhausting the air from which the carrier gas is removed are provided in the upper portion of the condenser 170, and a liquid carrier exhaust tube 173 for exhausting the liquid carrier is connected to one side of the condenser 170. The liquid carrier exhaust tube 173 is installed a predetermined height from the bottom of the condenser 170 for maintaining a constant height from the surface level of the liquid carrier contained in the condenser 170.
When the carrier gas is induced into the condenser 170 via the gas duct 171, the air is also induced inside the condenser 170. Here, the carrier gas is contacted with the cold liquid carrier to then be liquefied, and the air is exhausted outside via the air exhaust tube 174 while passing through the liquid carrier. A tan 191 is provided for discharging the air to the outside. The condensed liquid carrier is exhausted to the recovery reservoir 180 via the liquid carrier exhaust tube 173 positioned at a predetermined height at one side of the condenser 170.
A first pump 172 for pumping the carrier gas present within the collector 160 is installed at a predetermined position of the gas duct 171. Also, a second pump 182 for supplying the liquid carrier recovered in the recovery reservoir 180 to the development device is installed at a predetermined position of a liquid carrier supply tube 181.
In the condenser 170 for a carrier gas recovery apparatus of the aforementioned conventional imaging system, the collected carrier gas is simply injected into the cold liquid carrier contained in the condenser 170. The carrier gas injected into the liquid carrier is turned into bubbles, and the bubbles move upward to the surface level of the liquid carrier so as to contact the cold liquid carrier to then be condensed and liquefied.
However, since the bubbles are relatively large, the contact area with the liquid carrier is not sufficient. Also, due to the large size the bubbles move fast so that the contact time is not sufficient either. Thus, the carrier gas is not sufficiently liquefied. Since the carrier gas is not sufficiently liquefied, the recovery efficiency of the carrier gas is decreased. Accordingly, part of the carrier gas is not liquefied but is exhausted to the outside in a vapor state, which is harmful to humans.